1. Field of the Invention
The present invention relates to the field of the metallization of glass substrates for the manufacture of flat display screens. This metallization is used to form electrode arrays. These electrodes are opaque. They are generally made of silver.
2. Description of the Prior Art
Up till now, the metallization of the glass substrates designed for dense arrays of electrodes, with pitch values of less than 500 micrometers, have been made under vacuum by cathode spraying or vapor deposition. The deposited layer is relatively thick, ranging from one micrometer to a few micrometers, and the time taken for deposition in a vacuum chamber is relatively lengthy. The cost of such metallized substrates is relatively high, and this cost rises very quickly with the surface area of the substrates.
Novel methods of metallization that are less costly have been explored. These include, in particular, the photo-etching of layers of photosensitive or non-photosensitive silver composition. This method is not compatible with use on the front face of a display panel for it produces a yellow coloring in the glass substrate.
This is because there is a yellow-tinted zone located beneath the electrode and extending on either side of the electrode by about 30 to 50 micrometers. This zone is yellow-tinted because of the diffusion of silver in the glass.
The light received by the observer comes, on the one hand, from the light, produced by the electrical discharges within the panel, that is transmitted by the glass substrate and, on the other hand, from the light reflected by the electrodes. It is at the diffusion zones that the greatest part of the light perceived by the observer emerges.
This coloring, as in a yellow filter, greatly degrades the colorimetry of the color display panel. It is therefore not desirable that the light perceived should undergo yellow filtering.